In broadcast conditional access pay-TV systems, there is often a need to enforce specific position-based access criteria that are more fine-grained than the geographical resolution offered by the broadcast system's content distribution system. For example, content distribution via satellite is available over the footprint of the satellite and typically covers a very wide area. Over-the-top (OTT) content distribution service via Internet is basically available anywhere with an Internet connection. Recently, in the Chinese market, authorities want only the village population to receive content via satellite and people living in the cities to receive their content via cable.
Blackout is a well-known feature in conditional access systems. Blackout marks certain content as inaccessible by specific user devices. If the broadcaster knows where the customers live, the broadcaster can use this feature in order to prevent viewing by customers who live in certain areas. Blackout was typically used to block TV-viewing of sporting events taking place in some city by residents of that city. However, this feature has drawbacks including the broadcaster needs to know where each customer lives and a user may take the device and place it in another location. In satellite systems blackout was implemented and enforced by a secure device (e.g., a smart card) on the customer's premises. Thus the enforcement is based on a logical decision, not on cryptography per se, and generally requires the device to be secure.